A communication network includes network elements that route packets through the network, predominantly in line card hardware. Network packets may comprise carrier traffic and management traffic. Carrier traffic is typically data communicated by users of the communication network. On the other hand, management traffic is typically traffic associated with a provider of the communication network used for provisioning network equipment, tracking network status, monitoring alarms, and other network management functionality. Both carrier traffic and management traffic are communicated over the same physical medium using the same interfaces. Because management traffic is overlayed on the same physical network as carrier traffic, the management traffic must have a separate bandwidth allocation and addressing scheme from the carrier traffic. In addition, management traffic is generally limited to operations, administration, and management (OAM) and similar tasks, and is thus narrower in bandwidth than carrier traffic, yet management traffic must be guaranteed to ensure a network element may continuously be managed.
In many instances, communication networks may employ link aggregation. Link aggregation (e.g., IEEE 802.1AX-2008) may generally describe the practice of using multiple network cables or ports in parallel to increase the link speed beyond the limits of any one single cable or port, and to increase redundancy for higher availability. In link aggregation, a group or set of ports may be combined and represented as a single logical port to other components of the network system. Various switching elements of the network system may “see” the aggregated ports (known as a “link aggregation group” or “LAG”) as a single logical communication port in the routing tables or databases of network elements external to the LAG.
Despite the functional advantages of LAGs, LAGs may present challenges to communication of carrier traffic and management traffic for at least two reasons. First, as described above, carrier traffic and management traffic must often be segregated. Second, management traffic, while often requiring a minimum level of bandwidth, typically does not require all of the bandwidth of a LAG, meaning a LAG established to carry only management traffic would lead to wasted resources. Third, the physical ports may enter or leave a LAG group at any point without any effect on the logical state (e.g., “UP” or “DOWN”) of the LAG. Fourth, traffic which egresses onto multiple physical ports must arrive in the original serial packet order on the ingress logical LAG interface.
A network element for use in communications networks often use a “distributed” architecture in that multiple processing resources present within the network elements pass messages to each other, including messages regarding packet forwarding tables. Such an architecture often permits greater scalability and fault isolation, but may also add complexity to routing of management traffic in a LAG.